Hill stability of a triple system with an inner binary of large mass ratio

We determine the maximum dimensionless pericentre distance a third body can have to the barycentre of an extreme mass ratio binary, beyond which no exchange or ejection of any of the binary components can occur. We calculate this maximum distance, q '/ a , where q ' is the pericentre of the third mass to the binary barycentre and a is the semimajor axis of the binary, as a function of the critical value of   L ²  E   of the system, where L is the magnitude of the angular momentum vector and E is the total energy of the system. The critical value is obtained by calculating   L ²  E   for the central configuration of the system at the collinear Lagrangian points. In our case we can make approximations for the system when one of the masses is small. We compare the calculated values of the pericentre distance with numerical scattering experiments as a function of the eccentricity of the inner orbit, e , the mutual inclination i and the eccentricity of the outer orbit, e '. These show that the maximum observed value of   q '/ a   is indeed the critical q '/ a , as expected. However, when   e '→1  , the maximum observed value of q '/ a is equal to the critical value calculated when   e '=0  , which is contrary to the theory, which predicts exchange distances several orders of magnitude larger for nearly parabolic orbits. This does not occur because changes in the binding energy of the binary are exponentially small for distant, nearly parabolic encounters.     

Transient co-orbital asteroids

We analyze the orbital behavior of four new co-orbital NEOs and the Earth horseshoe object 2002 AA29. The new objects are 2001 CK32, a 3753 Cruithne-like co-orbital of Venus, 2001 GO2 and 2003 YN107, two objects with motion similar to 2002 AA29. 2001 CK32 is on a compound orbit. The asteroid reverses its path when the mean longitude difference is −50°. Its motion is chaotic. 2001 GO2 is an Earth HS orbiter with repeated transitions to the QS phase, the next occurring 200 years from now. The HS libration period is 190 years and the QS phases last 45 years. For 2002 AA29, our simulations permit us to find useful theoretical insights into the HS-QS transitions. Its orbit can be simulated with adequate accuracy for 4400 years into the future and 1483 years into the past. The new co-orbital 2003 YN107 is at present an Earth QS. It has entered this phase in 1997 and will leave it again in 2006, completing one QS cycle. Like 2002 AA29, it has frequent transitions between HS and QS. One HS cycle takes 133 years.     

InSAR datum connection using GNSS-augmented radar transponders

Deformation estimates from Interferometric Synthetic Aperture Radar (InSAR) are relative: they form a ‘free’ network referred to an arbitrary datum, e.g. by assuming a reference point in the image to be stable. However, some applications require ‘absolute’ InSAR estimates, i.e. expressed in a well-defined terrestrial reference frame, e.g. to compare InSAR results with those of other techniques. We propose a methodology based on collocated InSAR and Global Navigation Satellite System (GNSS) measurements, achieved by rigidly attaching phase-stable millimetre-precision compact active radar transponders to GNSS antennas. We demonstrate this concept through a simulated example and practical case studies in the Netherlands.     

Molecular approach to determine contributions of the protist community to particle flux

The importance of key taxonomic groups of eukaryotic phytoplankton as contributors to downward particle flux was evaluated near the European time-series station (ESTOC) in the eastern subtropical North Atlantic in March 2005. For the first time, molecular (cloning and sequencing) techniques were used to compare plankton communities from various depths in the euphotic zone with clone libraries from surface-tethered particle traps. Analyses of 18S rDNA clone libraries revealed compositional differences between the phytoplankton assemblages in the photic zone and those retrieved from shallow particle traps below, suggesting that not all phytoplankton contribute equally to particle flux. Contrary to expectations, our study also showed that it is not diatoms, despite their high abundance in the water column, but rather small phytoplankton taxa that dominated sequences recovered from trap material. We provide here first observational evidence that large taxa with mineral tests may not necessarily contribute more to export production than do smaller taxa even if the former are abundant in the water column.     

Seasonal and interannual dynamics in diatom production in the Cariaco Basin,Venezuela

We examine the diatom flux collected between November 1996 and April 1998, and between January and October 1999 at the time-series study site in the Cariaco Basin, off Venezuela. The temporal dynamics of the total diatom flux mainly reflect seasonal, trade wind-driven changes in surface hydrographic conditions, including changes associated with the El Niño/Southern Oscillation (ENSO). Highest diatom fluxes (>1.8×10⁷ valves m^?2 d^?1) coincided with the upwelling season in boreal winters 1997 and 1999. Changes in the composition of the diverse diatom community reflect variations in hydrographic and atmospheric conditions, as well as nutrient availability. Cyclotella litoralis, a neritic diatom typical of nutrient-rich waters, along with resting spores of several Chaetoceros spp., dominate during periods of high diatom flux, following trade wind-driven upwelling. During the boreal summers of 1997 and 1999, nutrient-depleted surface waters resulted in low diatom fluxes (<5.2×10⁶ valves m^?2 d^?1). The seasonal pattern of high diatom production was altered from July 1997 through April 1998, when the ENSO affected the Caribbean Sea. The occurrence of ENSO during boreal winter 1997–1998 caused a major change in the qualitative composition of the diatom assemblage: the highly diverse diatom assemblage was composed of a mixture of pelagic (Nitzschia bicapitata, Thalassionema nitzschioides var. inflata, T. nitzschioides var. parva, Azpeitia tabularis) and coastal species (C. litoralis, resting spores of Chaetoceros, T. nitzschioides var. nitzschioides). The simultaneous occurrence of neritic and open-ocean diatoms during boreal summers reflects the fact that the Cariaco Basin is influenced by both offshore and coastal waters, with considerable short-term variability in hydrographic conditions and nutrient availability.     

Consistent grain size distribution of pedogenic maghemite of surface soils and Miocene loessic soils on the Chinese Loess Plateau

There is agreement that ultrafine maghemite grains (<100 nm) are responsible for the magnetic enhancement of Chinese loess. Recent studies show that grain size distribution of ultrafine pedogenic maghemite grains within the aeolian sequences on the central Chinese Loess Plateau deposited in the last 8 Ma is consistent. However, whether the observed grain size distribution of ultrafine pedogenic maghemite grains can be observed in the western Chinese Loess Plateau and modern soils is not entirely clear. Here we find that young surface soil samples across the Chinese Loess Plateau and early Neogene loessic soils from the western Chinese Loess Plateau also show consistent grain size distribution with that of ultrafine pedogenic maghemite grains on the central Chinese Loess Plateau. The fact that young surface soil samples show apparent magnetic enhancement suggests that the ultrafine pedogenic maghemite grains derive from oxidation of ultrafine magnetite grains. Copyright © 2009 John Wiley & Sons, Ltd.     

Evaluation of Bias Associated with Capture Maps Derived from Nonlinear Groundwater Flow Models

The impact of groundwater withdrawal on surface water is a concern of water users and water managers, particularly in the arid western United States. Capture maps are useful tools to spatially assess the impact of groundwater pumping on water sources (e.g., streamflow depletion) and are being used more frequently for conjunctive management of surface water and groundwater. Capture maps have been derived using linear groundwater flow models and rely on the principle of superposition to demonstrate the effects of pumping in various locations on resources of interest. However, nonlinear models are often necessary to simulate head‐dependent boundary conditions and unconfined aquifers. Capture maps developed using nonlinear models with the principle of superposition may over‐ or underestimate capture magnitude and spatial extent. This paper presents new methods for generating capture difference maps, which assess spatial effects of model nonlinearity on capture fraction sensitivity to pumping rate, and for calculating the bias associated with capture maps. The sensitivity of capture map bias to selected parameters related to model design and conceptualization for the arid western United States is explored. This study finds that the simulation of stream continuity, pumping rates, stream incision, well proximity to capture sources, aquifer hydraulic conductivity, and groundwater evapotranspiration extinction depth substantially affect capture map bias. Capture difference maps demonstrate that regions with large capture fraction differences are indicative of greater potential capture map bias. Understanding both spatial and temporal bias in capture maps derived from nonlinear groundwater flow models improves their utility and defensibility as conjunctive‐use management tools.     

The effect of estrogen on cadmium distribution in rainbow trout (Oncorhynchus mykiss)

The effects of injections of 17β-estradiol (E2) and Cd, on the distribution of Cd and the induction of metallothionein (MT) mRNA and vitellogenin mRNA was investigated. Bone and liver were the main organs accumulating Cd. However, E2 redirected the metal accumulation from the bone and liver to the gill, gut and muscle upon exposure to E2. Cd did not induce the hepatic MT mRNA levels in animals treated with E2. The VTG mRNA levels were also reduced following co-injection of E2 and Cd. However, the kidney responded to Cd exposure by upregulating MT mRNA even in the presence of E2 treatment. In the liver the reduced MT mRNA induction led to a redistribution of CD from MT to non-MT proteins. The toxicological significance of these alterations in Cd handling remains to be determined.     

The Quaternary glacial sequence in Ecuador: a reinterpretation of the work of Walter Sauer

The Quaternary glacial sequence proposed for the Ecuadorian Andes by Walter Sauer is critically reviewed. Examination of his field evidence at sections exposing Quaternary sediments east of Quito has led to a fundamental reinterpretation. Deposits which Sauer considered as glacial, glacio-fluvial, glacio-lacustrine and pluvio-glacial in origin appear to have been formed mainly by volcanic, volcano-loessic, laharic, fluvial, colluvial and pedogenic processes.     

Spätvariszische Bruchsysteme im Hesperischen Massiv

Zusammenfassung Das Hesperische Massiv wurde von mehreren Bruchsystemen erfaßt, die durch ihre Häufigkeit und besonderen Charakter recht bedeutsam sind. Das wichtigste davon ist ein sich kreuzendes Bruchsystem mit NW-SE- und NE-SW-Streichen. Es handelt sich um spätvariszische Frakturen, die während des Mesozoikums und Tertiärs weiterhin aktiv gewesen sind. Über den ganzen variszischen Iberischen Block verbreitet findet man sehr häufig an diese Brüche gebundene Kluftsysteme.Die Störungen gaben Raum für Diabasgänge, sie haben die Intrusion von späten kalkalkalischen Graniten begünstigt, und sie haben Scherungen und Mylonitisierungen in den variszischen Gesteinen hervorgerufen.Setzt man die Lageveränderung des gesamten Hesperischen Massivs in Beziehung zum Kräftespiel an diesen Brüchen, so ist als verantwortlich für diese Deformation eine relative Drehbewegung des iberischen variszischen Sockels gegenüber dem französischen durchaus vorstellbar.

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The Hesperian Massif is affected by several systems of faults which are relevant both by their frequency and by their characteristics. Among these the most important is the system of conjugated faults striking NW-SE and NE-SW from late hercynian age which kept working during the Mesozoic and Tertiary periods. Systems of joints linked to these faults may be found very often throughout all the Iberian hercynian block.These features have originated diabasic dikes, have helped the intrusion of late calcoalcaline granite and have produced shearings and mylonitizations in the hercynian rocks.The analyse of the deformation of the Hesperian Massif as a whole in accordance with the work of these faults reveals a relative rotation of the Iberian hercynian socle by respect to the French one as the reason for this deformation.

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Resumen El Macizo hespérico se halla afectado por varios sistemas de fracturas que son importantes por su frequencia y caracteristicas. De estos el más importante es el sistema de fracturas conjugadas con direcciones NW-SE y NE-SW, de edad tardihercinica, que han seguido jugando durante el Mesozoico y el Terciario. Ligados a estas fracturas se encuentran con gran frecuencia sistemas de diaclasas distribuidos por todo el bloque hercmico ibérico. Estos accidentes han dado lugar a diques diabásicos, han favorecido la intrusión de granitos calcoalcalinos tardios y han producido cizallamientos y milonitizationes en las rocas hercínicas. Analizando la deformación del conjunto del Macizo Hespérico en función del juego de estas fracturas, puede suponerse como responsable de esta deformación una rotación relativa del zócalo hercínico ibérico respecto al francés.

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Résumé Le Massif Hespérique se trouve affecté plusieurs systèmes fractures qui sont importants par leur fréquence et par leur caractère. Parmi eux le plus important est le système de fractures conjugées en direction NW-SE et NE-SW de l'époque tardihercynienne qui s'est prolongé pendant les époques mesozoïque et tertiaire. Très souvent ces fractures sont liées à des systèmes de joints sur toute l'étendue du bloc hercynien Ibérique. Ces accidents ont été la raison de la formation de diques diabasiques, ont favorisé l'intrusion de granites calcoalcalins tardifs et ont produit des cisaillements et des mylonitisations dans les roches hercyniennes.En analysant la déformation de l'ensemble du Massif Hespérique en fonction du jeu de ces fractures, ont peut supposer comme cause de cette déformation une rotation relative du socle hercynien Ibérique par rapport au Français.

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Für die Herausgabe dieser Arbeit in deutscher Sprache ist der Autor Herrn Dr. G.Nollau in aufrichtigem Dank verbunden.